Copper alloy for plastic-working molds

ABSTRACT

Copper alloy for plastic-working molds, containing as other principal components aluminum, beryllium, silicon and cobalt, having a value of 9 to 18 weight percent, calculated by an aluminum conversion formula Al + 1.8 percent Be + 1.5 percent Si and 1.5 percent Co, all in weight percent, and containing 6 to 15 percent Al, 0.6 to 2 percent Be, 0.9 to 3.5 percent Si, 0.5 to 2.5 percent Co and the balance Cu, the alloy being characterized by readiness to be used in the as-cast state without being subjected to heat treatment, and having excellent wear resistance under load, as well as high toughness and other desirable mechanical properties. In some cases, the alloy may additionally contain as secondary elements at least one of the elements Sn, Zn, Mn, Fe and Zr. The alloys are particularly suitable for dies in deep drawing, which are required to have high mechanical strength and wear resistance.

United States Patent Watanabe et al.

1 1 Aug. 20, 1974 COPPER ALLOY FOR PLASTIC-WORKING MOLDS [75] Inventors:Seizo Watanabe, Kadoma; Minoru Maeda, Osaka; Masaru Yamaguchi,Nishinomiya, all of Japan [73] Assignee: Hitachi Shipbuilding andEngineering Co., Ltd., Osaka City, Japan [22] Filed: Apr. 3, 1972 [21]Appl. No.: 240,571

Related US. Application Data [63] Continuation-in-part of Ser. No.859,341, Sept. 19,

1969, abandoned.

[52] US. Cl 75/153, 75/154, 75/157.5, 75/ 162 [51] Int. Cl. C22c 9/10[58] Field of Search 75/153, 157.5, 160, 154, 75/156, 156.5, 157, 157.5,162; 148/32 [56] References Cited UNITED STATES PATENTS 1,920,699 8/1933Hurley 1,957,214 5/1934 Horstkotte.. 1,959,154 5/1934 Bremer 2,400,5665/1946 Misfeldt 75/159 3,201,234 8/1965 Scherbner et a1 75/157.53,459,544 8/1969 Watanabe 75/162 FOREIGN PATENTS OR APPLICATIONS PrimaryExaminer-Charles N. Lovell Attorney, Agent, or Firm-Tab T. Thein [5 7]ABSTRACT Copper alloy for plastic-working molds, containing as otherprincipal components aluminum, beryllium, silicon and cobalt, having avalue of 9 to 18 weight percent, calculated by an aluminum conversionformula Al 1.8 percent Be 1.5 percent Si and 1.5 percent Co, all inweight percent, and containing 6 to 15 percent A1, 0.6 to 2 percent Be,0.9 to 3.5 percent Si, 0.5 to 2.5 percent Co and the balance Cu, thealloy being characterized by readiness to be used in the as-cast statewithout being subjected to heat treatment, and having excellent wearresistance under load, as well as high toughness and other desirablemechanical properties. In some cases, the alloy may additionally containas secondary elements at least one of the elements Sn, Zn, Mn, Fe andZr. The alloys are particularly suitable for dies in deep drawing, whichare required to have high mechanical strength and wear resistance.

6 Claims, 4 Drawing Figures PATENTEBMIBZOW 3.830.644

' SHEET 2N7 2 FIG. 2

TENSILE STRENGTH CONTENT 0F COBALT (Wm) FIG. 3

COPPER ALLOY FOR PLASTIC-WORKING MOLDS This is a continuation-in-partapplication of application Ser. No. 859,341, filed Sept. 19, 1969, nowabandoned, which was titled Copper Base Alloys.

There are a number of hyper-eutectoid copperaluminum base alloys(aluminum bronze) which have been developed and proposed aswear-resistant materials.

In some of them a small amount of iron is added to improve the hardness,and in others a small amount of nickel, manganese, vanadium, etc. isadded to improve other mechanical properties.

The present invention relates to a highly wearresistant aluminum bronzeof the precipitationhardening type which, unlike the above-mentionedconventional aluminum-bronze materials, is prepared by adding aluminumto the copper base and a small amount of beryllium, silicon and cobalt,as more fully described hereinbelow.

The alloy of the present invention is further characterized in that thealuminum content can be decreased to a relatively low value in thehypo-eutectoid region without sacrificing the excellent wear resistance,therby achieving relatively high elongation.

Adding cobalt to Cu-Be alloys is already known, but from themetallurgical point of view, the cobalt addition in the alloy of thepresent invention is completely different from that in case of Cu-Bealloys as formerly employed. For further explanation of themetallurgical details, it may be mentioned that Cu-Be alloys are of.aging type in which the added cobalt is effective in regulating theboundary precipitation of Be in the aging well as their weakenedeutectoid structures. In order to utilize the y -phase, it is necessaryto refine and nodulate the 'y -phase and to regulate the eutectoidtransformation.

These effects are obtainable by the aid of the above mentioned Be, Siand Co addition. As a result of a series of our experiments concerningthe wear resistance of Cu-Al alloys, it has been clarified that such ametallurgical structure as [50 to 70 percent fine nodular 'y balance [3acicular a eutectoid (a 'y)] is most outstanding. On the other hand, inCU-Al binary alloys, the balance metallurgical structure, which isobtained by such an Al-quantity as will precipitate a 50 to 70 percent 7structure, is a coarse (a 'y) structure which cannot be practicallyutilized.

The alloy of the present invention is characterized in that theadditional elements are added so as to change their metallurgicalstructures from a structure as [coarse -y coarse (a 'y)] to saidexcellent structure consisting of [50 to 70 percent fine nodular 'ybalance [3 ac icular a eutectoid (a y)] in the as-cast state.Consequently, the alloy of the present invention is furthercharacterized in that the y-phase can be utilized even in a case whenCu-Al binary alloys have hypoeutectoid compositions.

As to the effect of each of the additional elements, the followingexplanation will further contribute to a clearer understanding.

Beryllium is added to regulate a transformation speed A of the eutectoid(a +7) phase, to leave a portion of the B-phase, and to aciculate ana-phase.

Co and Siar e added in order to refine and to nodulate a coarse'y-phase. The simultaneous addition of Co process However, in the ascast state this effect of and Si is intendedfor their mutualintensifying effect. addition is never noticeable for the Cu Be allowMoreover,Co-add1t1on strengthens the a-phase and the Contrary thereto,the alloy according to the present invention is characterized in that itcan be practically The following list shows the change of nodulated usedin the as-cast state, such as for plastic-working rates due to theaddition of Co or Si alone, or both Co v molds, and in this respect itis an improvement over the 40 and SI together.

Content Weight Cu Al Be Si Co Nodulated Al equivalent rate of v-p A 87.89 0.8 2.4 about 43 about 14 B 88.3 7.6 0.8 3.3 about 35 about 14 c 87.918.2 0.79 2.3 0.8 about 95 about 14.3

Note: Nodulated Rate J {total of i 'y-phase conventional high-hardnesscopper base alloys which are necessarily heat-treated before practicaluse. The Co-addition in the alloy of the present invention relates tothe precipitation behavior of the (Cu-Al) 'y -phase and does not relateto the precipitation behavior of Be. Therefore the Co-addition in thepresent invention must be considered to be completely novel as regardsmetallurgical conditions.

As seen from the above, the combined use of Si and Co leads to a farbetter result in the nodulated rate of the y-phase.

Copper base alloys containing as additives Be and Co are disclosed inUS. Pat. No. 3,201,234, dated Aug. I7, 1965, to P. J. Scherbner et al.,titled Alloy and Method of Producing the Same. However the alloysdescribed in the patent differ essentially from that of the presentinvention. In the alloys of the patent, titanium is a further additiveof prime importance. The range of Ti present in the alloys is 0.02 to0.2 and Co is in the range of 0.1 to 5 percent, that is, in an amounteffective to react with the titanium to form at least one of thecompounds TiCo, Ti Co and TiCo As explained in the patent theintermetallic compounds are present as nuclei of the grains of the alloyand the grain structure thus resulting is of materially greaterfineness. Contrary tothe addition of Ti and the formation of TiCointermetallic compounds, the present invention uses Co and Si asaddition. Co itself, that is to say, without any other additive, effectsthe refining of the y phase (primarily precipitated), but the effect Theadjustment of the components permits a variatron of the hardness in arange from the hardness of the conventional nickel-aluminum bronze toabout 400 H 1s enhanced by the s1multaneous addltion of Co and S1. 5Preferred Embodiments of the Invention For reasons set forth above thepresent alloy is partics me xamples of the present copper alloys areularly well suited for use as material for dies and rolls Shown in Table2 percentages y g in deep drawing, bending and rolling of such materialsI V as stainless steel, mild steel, nickel alloys, zinc alloys, TABLE 2aluminum alloys, plastics and others.

COMPOSITION OF THE ALLOYS ACCORDING TO A1 B6 5i C0 Cu Hardness THEINVENTION The resent alloy is co er base allo containin as l L3 BHNother p i'incipal componeiiti aluminum, beryllium,iili- 2 8 335 BHN conand cobalt. Permissible limits of the amounts of these components aregiven below 1n Table 1. In some AS mentioned above beryllium, Siliconand Cobalt cases some other elements may present as secon' arecharacteristic components of the present copper dary.components asfurther explamed below v alloy. These elements decrease the a-phaseregion in It is a feature common to each element that it accelth 1 t d al rat the rate of erates the precipitation of 7 in a Cu-Al alloy. Whenthe e p f i syshem an cce e 6 effect of aluminum for PromotingYa-Precipitation in a preclplt'fmon 0 t e CwA] alloy is assumed to beunity the effect of beryh Beryllium changes the ame lar eutectoidstructure to lium is 1.8 times that of aluminum, that of silicon 1.5ac'cular Structure and render? the structure finer times, and the effectof cobalt L5 times For example, S1l1con and cobalt render the matrixstructure finer and the figures 1, 1.8, L5 and 1.5 are Called aluminumalso cause prec1p1tates to form 1n spherical shape and equivalent.Consequently 'y -precipitation can be exm finer, gram Slze- These ekmemsare capable of pressed as the sum of aluminum equivalents of the P Preslstance of the alloys components or, in other words, as the formulafor alucordmg to h l i m' minum conversion. The conversion formula isThe permlsslble llmlts of the Components are as shown in Table 1. Withan aluminum content of less A] 13% Be 15% 15% C0 (all m Welght than 6percent, no precipitates are observed; if, on the other hand, theAlcontent exceeds 15 percent, precipiand it should be understood as anexperimentally detertateS are g atly increased in number a beCOme minedformula which aims to calculate the 'y coarser, thereby causing markeddecrease in the precipitation of the alloy. strength.

As a method to improve the wear resistance of the When the berylliumcontent is less than 0.6 percent, present alloys, it is necessary toadjust the precipitation the acicular structure, which is characteristicof the quantity of y If the value calculated by the above con- 40present copper alloys, does not appear; moreover, the Version formula isbelow the Precipitation of 72 is not wear resistance of the alloyscannot be improved. Hownoticeable. If, on the other hand, the value iSabove 18 ever when the Be content is higher than 2 percent, the theShape of the 72'P p becomes Coarse and acicular structure disappears anda considerable dethe Wear resistance 88 Well 35 the tel'lSile StrengthOf the rease in strength ccurs as in the case of an aluminum alloys aregreatly decreased. Therefore, the value of the Content of more than 5percent conversion formula is to be regulated 1n the range of 9 w theSilicon content is less than 09 percent, the to precipitate is neitherformed in spherical shape nor is The following Table l lndlcatespermissible limlts of it of fine grain Size but Whhn the Si Content ishigher component of the present copper alloy percent than 3.5 percent,the K-phase in the copper-silicon apages by weight). pears, which isundesirable.

When the cobalt content is less than 0.5 percent, the' TABLE 1precipitate is not in fine grain size and the tensile strength is notimproved. But when the Co content is Al Be 5i CO higher than 2.5percent, the aluminum equivalent of 6 I 5 06 2 9 3'5 05 to M balance 5 5cobalt changes into a negative number, and the precipi- 1 tation of the'y -phase is retarded. I Mechanical properties of further examples ofthe Characteristics of the present copper alloy are higher presentcopper alloy are shown in Table 3. These supehardness and wearresistance; in many cases, the tensile rior mechanical properties aregained not in the heatstrength and elongation are likewise improved. vtreated state but in the as-cast state.

TABLE 3 Example Al Be Si Co Cu Tensile Elongation Hardness H, strengthload 3000 kg kg/mm 6 8.2 0.79 2.3 2 86.71 65.2 0.3 360 BHN 7 7.3 0.6 1.51 89.6 53 4.1 300 BHN As shown in Table 3, the present copper alloy isvery hard. It will be further seen that the alloy in spite of being veryhard, is also very ductile.

A particular feature of the alloy is its superior wear resistance overthe conventional aluminum-ironcopper alloys, which is due to theaddition of beryllium, silicon and cobalt. The greatly improved wearresistance is, moreover, due to the very fine acicular structure of thematrix and the fine spherical precipitates.

Table 4 below shows the composition of a conventional aluminum-bronzealloy used in the comparison tests for wear resistance (in percentagesby weight).

most curve, that of the conventional alloy is shown, expressed in termsof the wear width, when a load was moved over the specimen at a slidingspeed of 0.94 m/second.

In FIG. 2, an alloy of the following composition was subjected totesting:

8.2 A1, 0.79 Be, 2.3 Si, 0.5 to 2.5 Co, balance copper.

In that figure, the effect of Co-addition on the tensile strength isillustrated. The content in cobalt is entered on the absicca in weightpercentage, the tensile strength on the ordinate in kglmm TheAl-equivalent is indicate on the right-hand side of the diagram. As

TABLE 4 mentioned before, the Co-contents of 0.5 to 2.5 weight percentare the satisfactory ones. Above 2.5 percent, A Fe Others Cu Hardness Hthe Al-equivalent of Co changes to a negative value and load 3000 kg theprecipitation of the 'y -phase is retarded.

In FIGS. 3 and 4, the test machine (Ogoshi-type 05 balance 325 BHN RapidTester) is shown to consist of a cylindrical disk A of stainless steel,on which a load P is applied in the direction of the arrow X. Thespecimen to be tested is designated by B, the wear width by the letterf. In the test, a sliding speed of 0.94 m/sec was applied, the load Inthe accompanying drawings, the superior wear rewas 2.8 to 25.5 kg.sistance of the alloy according to the invention as well From the curvesshowing the result of the wearas the role played by different amonts ofCo are more resistance test, it will be readily seen that the wear refll ill t d i th drawings, sistance of the present copper alloy isdecidedly far su- FIG. 1 is a graphic representation of test resultsPerior to the Conventional aluminum'iron'copper yshowing the wearresistance of the inventive alloy as compared to conventionalwear-resistant aluminum Whlle Present alloy descnbed above; an bronz;alloy containing Cu, Al, (I135; S11 and Co as the (principal components,we may a t ereto as secon ary e eadIZiIeGi; 2 shows the effect ofdifferent amounts of Co ments Sn Zn Mn l) Fe and Zr FIG 3 shows in fromView a rapid weamesting m 03). One or more of these additional elementsmay chine for carrying out the comparison tests, and be mcorporated nthe alloy. Test results have revealed FIG 4 is a Side View of themachine of i 3 that these additional elements have the following ef- FIGthree Specimens were Subjected to testing. fects on the copper alloyaccording to the invention. They are designated as Example A, Example Band conventional wear-resistant aluminum bronze. 4O EFFECT OF TINADDITION The composition of the specimens was as follows (in W 2 V.weight percent): Tin is effective to improve the wear resistance andExample Cu Al Be Si Co Sn Zr Zn A 87.91 8.2 0.79 2.3 0.8 B 84.59 8.70.6] 2.2 0.9 1.7 0 3 I replace a part of the silicon if the intendedobjects require this.

However if the Sn content is increased o ver the limit value, the wearresistance will be impaired. An example of proper Sn addition is shownin Table 5.

The value of wear width in Table 5 is a value f, expressed inmillimeters, and shown in FIG. 3. It will be understood that the smallervalue the wear width has the higher is the wear resistance.

TABLE 5 Al Be Si Co Sn Cu Hardness H Wear width 8.2 0.79 2.3 0.8 87.91340 MIN 2.88 8.2 0.78 2.2 0.8 2 86.02 360 BHN 2.35

Effect of Zinc Addition Zinc improves the tensile strength andelongation but if the amount added exceeds the limit value, theelongation will be greatly decreased. An example is shown in Table 6.

Effect of Manganese Addition Manganese improves the tensile strength butif the added amount exceeds the limit value, the tensile strength willbe decreased. An example is shown in- Table 7.

Effect of Iron Addition lron makes the grain size finer but if the addedamount exceeds the limit value, the wear resistance will be degraded.The limit value is up to 3 weight percent.

Effect of Zirconium Addition Zirconium makes the grain size finer, andeven if it is added in an amount exceeding its limit, the effect willremain unchanged.

The effect of two or more additional elements is shown in Table 8 below.

the as-cast state without being subjected to heat treatment, and havingexcellent wear resistance under load, and high toughness.

2. A copper base alloy consisting of 7.3 weight A1, 0.6 wt% Be, 1.5 wt%Si, 1 wt% Co, and 89.6 wt% Cu,

the alloy being characterized by readiness to be used in the as-caststate without being subjected to heat treatment, and having excellentwear resistance under load, and high toughness.

3. A copper base alloy consisting of 8.2 weight Al, v

0.78 wt% Be, 2.2 wt% Si, 0.8 wt% Co, 2 wt% Sn, additionally containingas secondary elements at least one of the elements: up to 5 wt% Zn, upto 5 wt% Mn, up to 3 wt% Fe, and up to 0.3 wt% Zr, and the balance Cuthe alloy being characterized by readiness to be used in the as-caststate without being subjected to heat treatment, and having excellentwear resistance under load, and high toughness.

4. A copper base alloy consisting of 8.1 weight Al, 0.81 wt% Be, 2.25wt% Si, 0.6 wt% Co, 2.5 wt% Zn, additionally containing as secondaryelements at least one of the elements: up to 5 wt% Sn, up to 5 wt% Mn,up to 3 wt% Fe, and up to 0.3 wt% Zr, and the balance Cu the alloy beingcharacterized by readiness to be used in the as-cast state without beingsubjected to heat treatment, and having excellent wear resistance underload, and high toughness.

5. A copper base alloy consisting of 8.2 wt% Al, 0.81 wt% Be, 2.2 wt%Si, 0.7 wt% Co, 2.5 wt% Mn, additionally containing as secondaryelements at least one of the elements: up to 5 wt% Sn, up to 5 wt% Zn,up to TABLE? Al Be Si Co Sn Zn Mn Zr Fe Cu Hardness Tensile strengthElongation BHN kg/mm 7.8 0.8 2 0.8 1.5 3.2 2 81.9 330 54.2 1 10.8 0.4 l5 2 1.8 0.3 83.2 350 57.8 0.5 7.5 L5 1 l 0.5 4.2 2 3 2.5 77.7 320 53.5 4

Wherever in the specification and claims the expression balance Cu isused it means that the Cu content,

3 wt% Fe, and up to 0.3 wt% Zr, and the balance Cu the alloy beingcharacterized by readiness to be used in while being within the limitrange defined in the main the as-cast state without being subjected toheat treatclaim, is dependent on the amount of secondary element orelements added to the principal components. In other words, the coppervalue in some examples, as well as in the appended claims, is given byomitting the respective amounts and values of the impurities present, ifany, such as for example 0.5 weight percent or less of Pb, P, As andpossibly others.

What we claim is:

l. A copper base alloy consisting of 8.2 weight Al, 0.79 wt% Be, 2.3 wt%Si, 2 wt% Co, and 86.71 wt% Cu, the alloy being characterized byreadiness to be used in ment, and having excellent wear resistance underload, and high toughness.

6. A copper base alloy consisting of 7.8 weight A1, 0.8 wt% Be, 2 wt%Si, 0.8 wt% Co, 1.5 wt% Sn, 3.2 wt% Zn, 2 wt% Mn, additionallycontaining as secondary elements at least one of the elements: up to 3wt% Fe, and up to 0.3 wt% Zr, and the balance Cu the alloy beingcharacterized by readiness to be used in the ascast state without beingsubjected to heat treatment,

- and having excellent wear resistance under load, and

high toughness.

5,850,644 n lu ust 2o, 974

Patent No Invento fls) S. Watangie et 8.1.

It is certified that err'or appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

I Column 5, line 56: numerical data in Table 1: for "$1", the correctvalues are 0.9 to 5.5 (instead of "9 and v cblumn 8, lines 25,155, 52and 62 (that is claims. 5, 5+, 5 and 6, lines 5,; for all claims),before "the alloy being char- -acterized" (or, after "balance Cu")insert commas Signed and sealed this 19th day of November 1974.

(SEAL) Attest:

McCOY M. GIBSON JR. C. MARSHALL DANN Attesting Officer Commissioner ofPatents FORM Po-wso (10-69) v USCOMWDC v V U.s. GOVERNMENT PRINTING OFFICE lll O3-33l

2. A copper base alloy consisting of 7.3 weight % Al, 0.6 wt% Be, 1.5wt% Si, 1 wt% Co, and 89.6 wt% Cu, the alloy being characterized byreadiness to be used in the as-cast state without being subjected toheat treatment, and having excellent wear resistance under load, andhigh toughness.
 3. A copper base alloy consisting of 8.2 weight % Al,0.78 wt% Be, 2.2 wt% Si, 0.8 wt% Co, 2 wt% Sn, additionally containingas secondary elements at least one of the elements: up to 5 wt% Zn, upto 5 wt% Mn, up to 3 wt% Fe, and up to 0.3 wt% Zr, and the balance Cuthe alloy being characterized by readiness to be used in the as-caststate without being subjected to heat treatment, and having excellentwear resistance under load, and high toughness.
 4. A copper base alloyconsisting of 8.1 weight % Al, 0.81 wt% Be, 2.25 wt% Si, 0.6 wt% Co, 2.5wt% Zn, additionally containing as secondary elements at least one ofthe elements: up to 5 wt% Sn, up to 5 wt% Mn, up to 3 wt% Fe, and up to0.3 wt% Zr, and the balance Cu the alloy being characterized byreadiness to be used in the as-cast state without being subjected toheat treatment, and having excellent wear resistance under load, andhigh toughness.
 5. A copper base alloy consisting of 8.2 wt% Al, 0.81wt% Be, 2.2 wt% Si, 0.7 wt% Co, 2.5 wt% Mn, additionally containing assecondary elements at least one of the elements: up to 5 wt% Sn, up to 5wt% Zn, up to 3 wt% Fe, and up to 0.3 wt% Zr, and the balance Cu thealloy being characterized by readiness to be used in the as-cast statewithout being subjected to heat treatment, and having excellent wearresistance under load, and high toughness.
 6. A copper base alloyconsisting of 7.8 weight % Al, 0.8 wt% Be, 2 wt% Si, 0.8 wt% Co, 1.5 wt%Sn, 3.2 wt% Zn, 2 wt% Mn, additionally containing as secondary elementsat least one of the elements: up to 3 wt% Fe, and up to 0.3 wt% Zr, andthe balance Cu the alloy being characterized by readiness to be used inthe as-cast state without being subjected to heat treatment, and havingexcellent wear resistance under load, and high toughness.